Thread: 3% CO on LM-1
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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
My two cents for what it is worth.

Two reasons to run CO fat at idle. One is to try compensate some what for the lean surge that comes with applying the throttle as CIS dose not have anything like an accelerator pump to keep the AFR's near an ideal 13.2 for max torque. Some CIS motors do have provision for lowering control pressure with acceleration to try to minimize this. The 3.0 turbo through 77 did.

The other is it adds some fuel to the AFR's on boost to help minimize the lean section that comes in the later part of the RPM's.

I would not be to concerned with a fat idle unless one spends a lot of time at stop lights. I would be more concerned with my AFR's on cruse if it is a car that is going to see a fair amount of street driving.

It might be possible to dial in the AFR's for max TQ off idle and off curse with acceleration and then plug the O2 back in to bring them back for better fuel economy. I it just depends on how far one goes as to if the Lambda computer can compensate that much. The when the TPS indicates acceleration, the 02 would be pulled out of the loop and one would have there proper acceleration fuel.

I built my own electronic WUR using an Andial Frequency valve that lowered control pressure with acceleration to moderate the lean surge when still keeping my idle and cruse AFR's in the 14's. The new D-WUR should be able to do the same thing. This can also be done by converting the WUR to vacuum sensing.
Old 11-21-2009, 08:51 AM
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